Qualification > Reference Material
AS BIOLOGY ( C.I.E ) Notes
Romeesa-Chan:
--- Quote from: Kimo Jesus on October 03, 2011, 03:38:13 pm ---haha thanks for the rep =]!
--- End quote ---
Welcome ... ;D
Keep the notes coming! :D
silvercameron:
hey your notes are reallyy good.=).but could you upload them in a way that i can download them in pdf format?pls?
Besides even i have started my A/AS level in september.so i need all help i can get.iwanna know which books you study from.i have got the cie biology revision guide and its really helpful.i will definitely post the link from where u'll be able to download it but i cant find at the moment.i'll post it soon.
Revision guides are a must for studying A level subjects.but i'm not able to find them for chem and phy.do you know where i can download them from?
P.S. Could you give me some references?
Thanks.=)
WARRIOR:
GENETIC CONTROL AND INHERITENCE Contd.
Chromosomes
* A Double structure made of two identical CHROMATIDS ( due to semi-conservative replication of DNA in interphase )
* Each Chromatid has one DNA & HISTONES (proteins)
* Chromatids are held by a CENTROMERE at a POSITION CHARACTERISTIC to a PARTICULAR CHROMOSME
* It is linear and only visible during nuclear devision ---------------------------------------------------------------------------------------
Mitosis
Daughter cells have same number of chromosomes as parent cells
Daughter cells are genetically identical
Uses of mitosis:
Growth of somatic cells and zygote
Repair of tissues and replacement of cells
Basis of asexual reproduction
NOTE : Interphase is not a stage of mitosis !
Interphase
* DNA replicates
* Centriole replicate
* Cell builds up energy for all stages
* Cell grows to normal size
Starting from here mitosis begins.SEE DIAGRAMS ALSO.
1. PROPHASE
* Chromosomes coil up , become shorter , thicker , denser , take more stain and become visible
* Nucleolus and nuclear envelope disappear
* Centrioles start moving to poles 2.Metaphase
* Centrioles reach poles and forms spindle
* Chromosomes line up at equator of spindle fibres that attaches to their centromeres 3.Anaphase
* Centromeres divide into two
* Chromatids move to opposite poles , centromeres first by shortening of spindle microtubules4.Telophase
* Chromatids at poles will now uncoil to form chromatin. DNA will replicate in interphase
* Cytokinesis : Constriction of cell membrane to divide cytoplams and cell into two
* Nuclear envelope and nucleolus reappear
Meiosis
Reduction division to make gametes as it
halves the number of chromosomes , so gametes are haploid to fuse in fertilisation to give zygote
Causes genetic variation
----------------------------------------------------------------------------------------
Oncogenes : The mutated form of genes that control cell divison
Carcinogens : Factors that increase chance cancer
Mutagens : Factor that increase chance of mutations
Genetic mutation
Carcinogens combine with DNA
Genetic mutation occurs in a gene that control cell division
Oncogenes made
Cancerous cell appears
Divided repeatedly and rapidly by mitosis and it is different in shape and size from cells
Malignant tumor forms and enlarges and is supplied by blood and lymphatic vessels
It's malignant cells spread 1.directly to surrounding tissues 2. by lymphatics 3 by blood vessels to give metastasis in distant organs
Carcinogens
1.Chemicals : Carcinogens in tar of tobacco smoke
2.Radiations : X-rays
4.Virus infection : Cancer of cervix
5.Hereditary predispositions: The susceptibility to carcinogens is inherited but cancer itself is not.
silvercameron:
thanks for your info.=)here is the download link for cie biology revision guide
http://ebookee.org/go/?u=http://depositfiles.com/files/u2nlaaw9u
just go to this link and click 'free downloading'.
you are lucky that you 've got a teacher who gives you excellent notes.my teachers dont give us priper notes at all!!!!infact they just make us write whatever is in the book!!!whats the point?thats why i have to rely on revision guides and other references.
From whereever i have searched i cant find the cie revision guides maybe cuz they were published this year in jan.anyways,if you find the guides or anyone else you know does pls let me know and thanks for your help.
Keep posting more notes.
WARRIOR:
Energy and EcosystemHabitat : A place where an organism lives
Niche : Role of an organism in an ecosystem
Population : A group of organisms of same species at the same place at the same time and can interbreed
Community : All organisms of all species living in a habitat
Ecosystem : An interacting community of living organisms and the non-living parts of the
environment with which they interact
Producer : Organism that obtains light energy .That gets is carbon from an inorganic source (C02) . Has chlorophyll . Does photosynthesis . Makes it's own food
Consumer : Organism that obtains chemical energy. That gets it's carbon from an organic source.Does not have chlorophyll , does not photosynthesise . Takes it's food from other organisms
Decomposer : Organism that obtains chemical energy . Gets it's carbon from an organic source by secreting enzymes of dead organsims and digesting them to liquid form and absorbing it.
Food Chain : Diagram showing the flow of food and energy between organisms in linear form
Food web : Diagram showing flow of food and energy between organisms in network form (shows all food chains )
Trophic level : The feeding position of an organism in a food chain or a food web
Gross Primary Productivity : Total amount of light energy converted to chemical energy
Net Primary Productivity : Total amount of Chemical energy left after a plant does respiration.
Energy loss in producer by : Heat loss & Respiration
Energy loss by primary consumer : Not all plant are eaten
Respiration and heat loss
Defaecation
Excretion
Energy loss by secondary consumer : Respiration & heat loss
Defaecation
Exctretion
Nitrogen Cycle
Nitrogen fixation : By Rhizobium in nodules and in soil , Lightning , Haber Process
Decomposition and Ammonification : By Decomposer Bacteria and fungi
Nitrification of Ammonium into Nitrites : Nitrosomonas
Nitrification of Nitrites into Nitrates : Nitrobacter
Denitrification : By denitrifying bacteria
Nitrogen from airs turns into :
1.ORGANIC NITROGEN in leguminous plants (By bacteria in root nodules of leguminous plants , RHIZOBIUM by nitrogen fixation ) . The plants then die and turn into HUMUS ( ORGANIC N in soil ) . OR the plant gets eaten by animals who EITHER die and turn into HUMUS or excrete UREA into soil. The UREA and HUMUS turns into AMMONIUM in soil by decomposition and ammonification ( By decomposer bacteria and fungi ) . The AMMONIUM in soil turns into NITRITES by Nitrification ( By nitrifying bacteria called NITROSOMONAS) . NITRITES are turned into NITRATES by Nitrification ( By Nitrifying bacteria called [/u]NITROBACTER) [/u].NITRATES are either absorbed by plants or leached into waterways or are turned into NITROGEN GAS by Denitrification (By Denitrifying Bacteria )
2.ORGANIC NITROGEN by nitrogen fixation ( By nitrogen-fixing bacteria living in soil , Rhizobium ) . The ORGANIC NITROGEN is then turned to AMMONIUM in soil by decomposition and ammonification ( By decomposer bacteria and fungi ) . The AMMONIUM in soil turns into NITRITES by Nitrification ( By nitrifying bacteria called NITROSOMONAS) . NITRITES are turned into NITRATES by Nitrification ( By Nitrifying bacteria called [/u]NITROBACTER) [/u].NITRATES are either absorbed by plants or leached into waterways or are turned into NITROGEN GAS by Denitrification (By Denitrifying Bacteria ).
[u3.]AMMONIUM SALTS AND NITRATES [/u] by nitrogen fixation ( By Haber process ).The Nitrates enter the soil as Nitrates . And the AMMONIUM SALTS is then turned to AMMONIUM in soil by decomposition and ammonification ( By decomposer bacteria and fungi ) . The AMMONIUM in soil turns into NITRITES by Nitrification ( By nitrifying bacteria called NITROSOMONAS) . NITRITES are turned into NITRATES by Nitrification ( By Nitrifying bacteria called [/u]NITROBACTER) [/u].[/u].NITRATES are either absorbed by plants or leached into waterways or are turned into NITROGEN GAS by Denitrification (By Denitrifying Bacteria ).
4.NITRATES by LIGHTNING [ Also Nitrogen fixation ][/u].NITRATES are either absorbed by plants or leached into waterways or are turned into NITROGEN GAS by Denitrification (By Denitrifying Bacteria ).
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